EP0102819A1 - Bariumferrit-Teilchen für magnetische Aufzeichnungsmedien - Google Patents

Bariumferrit-Teilchen für magnetische Aufzeichnungsmedien Download PDF

Info

Publication number
EP0102819A1
EP0102819A1 EP83304976A EP83304976A EP0102819A1 EP 0102819 A1 EP0102819 A1 EP 0102819A1 EP 83304976 A EP83304976 A EP 83304976A EP 83304976 A EP83304976 A EP 83304976A EP 0102819 A1 EP0102819 A1 EP 0102819A1
Authority
EP
European Patent Office
Prior art keywords
particles
barium ferrite
surface area
specific surface
ferrite particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83304976A
Other languages
English (en)
French (fr)
Other versions
EP0102819B1 (de
Inventor
Norimichi Nagai
Nanao Horiishi
Masao Kiyama
Toshio Takada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toda Kogyo Corp
Original Assignee
Toda Kogyo Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=15540741&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0102819(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Toda Kogyo Corp filed Critical Toda Kogyo Corp
Publication of EP0102819A1 publication Critical patent/EP0102819A1/de
Application granted granted Critical
Publication of EP0102819B1 publication Critical patent/EP0102819B1/de
Expired legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
    • G11B5/70678—Ferrites

Definitions

  • the present invention relates to barium ferrite particles of magnetic properties, especially not more than 1,000 Oe of a coercive force suitable for use as a magnetic material for magnetic recording. And the present invention relates to a process for producing the barium ferrite particles.
  • the barium ferrite particles have been obtained by igniting a mixture of iron(III) oxide and barium carbonate at high temperature in the air, and the thus-produced particles have more than 3,000 Oe of the coercive force. Therefore, such a barium'ferrite particles are not suitable for use as the magnetic material for magnetic recording and in fact they are widely used as a permanent magnet.
  • Another method for producing the barium ferrite particles comprises subjecting an alkaline suspension containing ferric ions and barium ions to autoclaving.
  • a ferromagnetic precipitate, barium ferrite, consisting of hexagonal plate-like particles can be obtained and at the same time non- ferromagnetic precipitates, a-Fe 2 0 3 , are also formed depending on the reaction conditions.
  • the magnetic properties of the ferromagnetic particles obtained also widely vary since a variety of the particles in particle size are produced depending on the reaction conditions. Therefore, the barium ferrite particles having the magnetic properties suitable for use as the magnetic material for magnetic recording can be hardly obtained by this method.
  • An object of the present invention is to improve the latter method so as to obtain the barium ferrite particles having the magnetic properties suitable for use as the magnetic material for magnetic recording.
  • Specific surface area is intended to refer to the value measured by the BET method.
  • Coercive force is intended to refer to the value measured at a degree of packing density of 1.6 g/cm 3 .
  • Maximum magnetization is intended to refer to the value measured by the VSM method at the magnetic field of 10 kOe.
  • Apparent density and “tap density” are intended to refer to the values measured following JIS K 5101.
  • the barium ferrite particles with different specific surface area were produced by changing the reaction conditions, such as temperature, kinds and concentrations of the starting materials, etc., which were used in the experiment. Then, the magnetic properties of the particles obtained were measured and the results were as shown in Figs. 1 and 2.
  • Fig. 1 shows a relation between the maximum magnetization of the barium ferrite particles and the specific surface area thereof and Fig. 2 shows a relation between the coercive force and the specific surface area.
  • the specific surface area of the barium ferrite particles should be at most 5 m 2 /g to obtain the particles of not more than 1,000 Oe of the coercive force.
  • the barium ferrite particles produced have the specific surface area of 0.5 to 5.0 m 2 /g and so the coercive force thereof is not more than 1,000 Oe, which is suitable for use as the magnetic material for magnetic recording.
  • the maximum magnetization of the barium ferrite particles of the present invention is 35 to 60 emu/g.
  • the barium ferrite particles with the specific surface area of less than 0.5 m 2 /g have the suitable coercive force, but they are not preferable since the particle size thereof is large. And the barium ferrite particles with the specific surface area of more than 5.0 m 2 /g are not preferable due to their unsuitable coercive force.
  • the specific surface area thereof is preferably 2 to 4 m 2 /g and the maximum magnetization thereof is preferably 42 to 47 emu/g.
  • the barium ferrite particles in a form of plate-like having the specific surface area of 0.5 to 5.0 m 2 /g of the present invention can be produced by subjecting the alkaline suspension containing the acicular particles of a-FeO(OH) with the specific surface area of 10 to 25 m 2 /g and barium ions to autoclaving at a temperature of 250 to 360°C.
  • the acicular particles of ⁇ -FeO(OH) used. as the starting material have the specific surface area of 10 to 25 m 2 /g, preferably 15 to 18 m 2 /g.
  • the barium ferrite particles of the coercive force of 600 to 800 Oe it is desirable that the acicular particles of a-FeO(OH) with the specific surface area of 15 to 18 m 2 /g are used.
  • the acicular particles in the suspension they have preferably an apparent density of not more than 0.08 g/cm and/or a tap density of not more than 0.2 g/cm 3 .
  • the barium ferrite particles with the desired specific surface area cannot be naturally produced.
  • the acicular particles of a-FeO(OH) are present in the suspension in an amount of at least 6 times based on the amount of the barium ions and calculated as the atomic ratio of Fe(III) to Ba.
  • the acicular particles of a-FeO(OH) are present in the suspension in an amount of 6 to 8 times based on the amount of the barium ions and calculated as the atomic ratio of Fe(III) to Ba.
  • the pH of the alkaline suspension is over 11, preferably 13 to 14. When the pH of the suspension is not more than 11, the reaction system is unsuitable to obtain the desired particles.
  • the reaction temperature is 250 to 360°C, preferably 280 to 320°C.
  • the reaction temperature is not more than 250°C, the incomplete reaction is caused and thereby the desired particles can be difficultly produced.
  • the temperature of more than 360°C is above the critical temperature and it is not favorable.
  • the barium ferrite particles with the specified specific surface area are easily and constantly produced, and the thus-produced barium ferrite particles have not more than 1,000 Oe of the coercive force while maintaining high maximum magnetization. Accordingly, the barium ferrite particles of the present invention are favorably suitable as the magnetic material for magnetic recording. They are particularly suitable as the magnetic material for perpendicular magnetic recording since the c axis thereof is the easy direction of magnetization.
  • An alkaline suspension was prepared in an autoclave by mixing 25.6 g (0.640 mol) of acicular particles of a-FeO(OH) with specific surface area of 16.7 m 2 /g, apparent density of 0.07 g/cm and tap density of 0.20 g/cm 3 , 25.2 g (0.08 mol) of barium hydroxide octahydrate and 42.0 g (1.05 mol) of sodium hydroxide in 700 ml of decarbonated water.
  • the alkaline suspension was heated to 320°C under a pressure of 110 kg/cm 2 , and kept at this temperature for 5 hours.
  • the precipitate was separated by filtration, washed thoroughly with water and dried at 80°C to obtain the ferromagnetic brown particles.
  • An alkaline suspension was prepared in an autoclave by mixing 0.647 mol of acicular particles of a-FeO(OH) with the specific surface area of 15.9 m 2 /g, apparent density of 0.08 g/cm and tap density of 0.20 g/cm 3 , 0.08 mol of barium hydroxide octahydrate and 1.05 mol of sodium hydroxide in 700 ml of decarbonated water.
  • the alkaline suspension was heated to 300°C under a pressure of 80 kg/cm 2 , and then stirred at 600 r.p.m. for 3 hours.
  • the precipitate was separated by filtration, washed thoroughly with water and dried at 80°C to obtain the ferromagnetic brown particles.
  • the coercive force of the barium ferrite particles was measured at the degree of packing density of 1.6 g/cm 3 .
  • the c axis of the barium ferrite particles is the easy direction of magnification and therefore the coercive force largely depends on the degree of packing density as shown in Fig. 5.
  • the magnetic tape having the desired coercive force can be obtained by suitably adjusting the degree of packing density on producing the magnetic tape, in particular the perpendicular magnetic recording tape even if the barium ferrite particles used as the magnetic material have relatively small coercive force.

Landscapes

  • Compounds Of Iron (AREA)
  • Hard Magnetic Materials (AREA)
  • Magnetic Record Carriers (AREA)
  • Paints Or Removers (AREA)
EP83304976A 1982-08-31 1983-08-30 Bariumferrit-Teilchen für magnetische Aufzeichnungsmedien Expired EP0102819B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP57152448A JPS5941806A (ja) 1982-08-31 1982-08-31 磁気記録用板状Ｂａフエライト粒子粉末の製造法
JP152448/82 1982-08-31

Publications (2)

Publication Number Publication Date
EP0102819A1 true EP0102819A1 (de) 1984-03-14
EP0102819B1 EP0102819B1 (de) 1986-12-30

Family

ID=15540741

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83304976A Expired EP0102819B1 (de) 1982-08-31 1983-08-30 Bariumferrit-Teilchen für magnetische Aufzeichnungsmedien

Country Status (5)

Country Link
US (1) US4539129A (de)
EP (1) EP0102819B1 (de)
JP (1) JPS5941806A (de)
KR (1) KR890001120B1 (de)
DE (1) DE3368804D1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0116449A3 (en) * 1983-02-05 1985-12-18 Toda Kogyo Corp Barium ferrite particles for magnetic recording media
US4561988A (en) * 1983-10-31 1985-12-31 Toda Kogyo Corporation Process for production of plate-like barium ferrite particles for magnetic recording
US4671885A (en) * 1984-12-11 1987-06-09 Centre National De La Recherche Scientifique Process for the preparation of magnetized hexagonal ferrites, use of these ferrites as base materials for magnets or for magnetic recording
US4781852A (en) * 1986-10-24 1988-11-01 Olin Corporation Process for making selected doped barium and strontium hexaferrite particles
EP0610077A1 (de) * 1993-02-04 1994-08-10 Kabushiki Kaisha Toshiba Magnetpulver und dieses Pulver verwendender magnetischer Aufzeichnungsträger mit hoher Dichte

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3417793A1 (de) * 1984-05-14 1985-11-14 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung feinteiliger, nadelfoermiger und hochkoerzitiver hexagonaler ferrite sowie ihre verwendung zur herstellung magnetischer aufzeichnungstraeger und plastoferrite
JPS62176921A (ja) * 1986-01-29 1987-08-03 Toda Kogyo Corp 板状Ｂａフエライト微粒子粉末の製造法
EP0232132B1 (de) * 1986-01-29 1991-10-02 Toda Kogyo Corp. Plättchenförmige Bariumferritteilchen für magnetische Aufzeichnung und Verfahren zu ihrer Herstellung
US4780232A (en) * 1986-10-24 1988-10-25 Olin Corporation Process for preparing selected, doped magnetite/carbonate co-precipitates
US4828916A (en) * 1986-12-27 1989-05-09 Toda Kogyo Corporation Plate-like magnetoplumbite type ferrite particles for magnetic recording and magnetic recording media using the same
JPH0770040B2 (ja) * 1987-09-30 1995-07-31 富士写真フイルム株式会社 磁気記録媒体
CN1250322C (zh) * 2004-06-11 2006-04-12 成都天立化工科技有限公司 采用三段变压吸附装置从空气中分离氮气和氧气的方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2140320A1 (de) * 1970-08-12 1972-10-19 Minnesota Mining & Mfg Flexible Permanentmagnete und Verfahren zur Herstellung von Bariumferritteilchen für Magnete
CH532824A (de) * 1968-03-05 1973-02-28 Philips Nv Verfahren zum Erhöhen der Koerzitivkraft und/oder der Remanenz eines hart-magnetischen Pulvers
EP0039773A1 (de) * 1980-05-08 1981-11-18 Kabushiki Kaisha Toshiba Verfahren zur Herstellung eines Pulvers der Bariumferrit-Reihe
EP0045028A2 (de) * 1980-07-29 1982-02-03 Bayer Ag Verfahren zur Herstellung magnetischer Eisenoxide

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4226843A (en) * 1979-03-30 1980-10-07 Dowa Mining Co., Ltd. Process and apparatus for production of spherical grain ferrite powder
JPS5667904A (en) * 1979-11-08 1981-06-08 Toshiba Corp Preparation method of megnetic powder for high density magnetic recording
DE3042959A1 (de) * 1980-11-14 1982-07-08 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung von feinteiligem hochkoerzitivem bariumferrit, sowie seine verwendung zur herstellung von magnetischen aufzeichnungstraegern
JPS6051243B2 (ja) * 1981-05-30 1985-11-13 戸田工業株式会社 磁気記録材料用磁性酸化鉄粒子粉末の製造法
EP0072437B1 (de) * 1981-08-19 1987-01-07 BASF Aktiengesellschaft Verfahren zur Herstellung feinteiliger Ferritpulver

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH532824A (de) * 1968-03-05 1973-02-28 Philips Nv Verfahren zum Erhöhen der Koerzitivkraft und/oder der Remanenz eines hart-magnetischen Pulvers
DE2140320A1 (de) * 1970-08-12 1972-10-19 Minnesota Mining & Mfg Flexible Permanentmagnete und Verfahren zur Herstellung von Bariumferritteilchen für Magnete
EP0039773A1 (de) * 1980-05-08 1981-11-18 Kabushiki Kaisha Toshiba Verfahren zur Herstellung eines Pulvers der Bariumferrit-Reihe
EP0045028A2 (de) * 1980-07-29 1982-02-03 Bayer Ag Verfahren zur Herstellung magnetischer Eisenoxide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SOVIET INVENTIONS ILLUSTRATED, section Ch, week C 03, February 27,1980 DERWENT PUBLICATIONS LTD., London L 03 page 3; & SU-A-660101 (AIZIKOVICH) *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0116449A3 (en) * 1983-02-05 1985-12-18 Toda Kogyo Corp Barium ferrite particles for magnetic recording media
US4561988A (en) * 1983-10-31 1985-12-31 Toda Kogyo Corporation Process for production of plate-like barium ferrite particles for magnetic recording
US4671885A (en) * 1984-12-11 1987-06-09 Centre National De La Recherche Scientifique Process for the preparation of magnetized hexagonal ferrites, use of these ferrites as base materials for magnets or for magnetic recording
US4781852A (en) * 1986-10-24 1988-11-01 Olin Corporation Process for making selected doped barium and strontium hexaferrite particles
EP0610077A1 (de) * 1993-02-04 1994-08-10 Kabushiki Kaisha Toshiba Magnetpulver und dieses Pulver verwendender magnetischer Aufzeichnungsträger mit hoher Dichte
US5576114A (en) * 1993-02-04 1996-11-19 Kabushiki Kaisha Toshiba High density magnetic recording medium containing hexagonal system ferrite powder
US5766763A (en) * 1993-02-04 1998-06-16 Kabushiki Kaisha Toshiba Hexagonal system ferrite powder for a high density magnetic recording medium

Also Published As

Publication number Publication date
US4539129A (en) 1985-09-03
KR840006174A (ko) 1984-11-22
JPS5941806A (ja) 1984-03-08
DE3368804D1 (en) 1987-02-05
JPS6311763B2 (de) 1988-03-16
KR890001120B1 (ko) 1989-04-24
EP0102819B1 (de) 1986-12-30

Similar Documents

Publication Publication Date Title
EP0123445B2 (de) Bariumferritteilchen für magnetische Aufzeichnungsträger
KR890005137B1 (ko) 자기 기록용 판상 바륨페라이트 입자와 그의 제조방법
US4539129A (en) Barium ferrite particles and process for producing said particles
US3770500A (en) Magnetic materials and method of making same
EP0141558B2 (de) Verfahren zur Herstellung von Bariumferritteilchen für magnetische Aufzeichnungsträger
US4584242A (en) Plate-like barium ferrite particles for magnetic recording and process for producing the same
US5075169A (en) Plate-like composite ferrite particles for magnetic recording and process for producing the same
US4529524A (en) Process for producing plate-like barium ferrite particles for magnetic recording
US5766763A (en) Hexagonal system ferrite powder for a high density magnetic recording medium
EP0247681B1 (de) Magnetisches Material, magnetischer Aufzeichnungsträger und Methode zur Herstellung eines magnetischen Materials
GB1559145A (en) Acicular ferromagnetic metal particles and method for preparation of the same
EP0515749B1 (de) Verfahren zur Herstellung von nadelförmigen Goethit-Teilchen und nadelförmigen magnetischen Eisenoxid-Teilchen
EP0075991A3 (de) Magnetisches Aufzeichnungsmedium und Verfahren zu seiner Herstellung
US5480571A (en) Process for producing acicular goethite particles and acicular magnetic iron oxide particles
JPH0469091B2 (de)
JPH0380725B2 (de)
US5238483A (en) Acicular magnetic iron based alloy particles for magnetic recording and method of producing the same
JPH07120577B2 (ja) 磁気記録用板状Ｂａフエライト微粒子粉末及びその製造法
JPS62108736A (ja) 強磁性粉末の製造方法
EP0366370A2 (de) Plättchenförmige feine Oxidgemengeteilchen, hauptsächlich Ba und Fe enthaltend sowie Verfahren zur Herstellung derselben
JPH0377642B2 (de)
JPH03252316A (ja) 磁気記録用板状Ｓｒフェライト微粒子粉末及びその製造法
JPH0764567B2 (ja) 磁気記録用板状マグネトプランバイト型フエライト微粒子粉末
JPH02284403A (ja) 比較的温度依存性のない保磁力を有する微細粉砕された磁性ヘキサフエライト及びその用途
JPH0647469B2 (ja) 高密度記録用フェライト粉末

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR GB NL

17P Request for examination filed

Effective date: 19840425

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB NL

REF Corresponds to:

Ref document number: 3368804

Country of ref document: DE

Date of ref document: 19870205

ET Fr: translation filed
PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

26 Opposition filed

Opponent name: BASF AKTIENGESELLSCHAFT, LUDWIGSHAFEN

Effective date: 19870925

NLR1 Nl: opposition has been filed with the epo

Opponent name: BASF AKTIENGESELLSCHAFT

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19890808

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19890831

Year of fee payment: 7

Ref country code: GB

Payment date: 19890831

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19891002

Year of fee payment: 7

RDAG Patent revoked

Free format text: ORIGINAL CODE: 0009271

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: PATENT REVOKED

27W Patent revoked

Effective date: 19891118

GBPR Gb: patent revoked under art. 102 of the ep convention designating the uk as contracting state
NLR2 Nl: decision of opposition